Serum beta 2-microglobulin and prognosis of patients with renal cell carcinoma.

Beta 2-Microglobulin (beta 2-M) was analysed in serum of 145 patients with renal cell carcinoma, and serum creatinine < 125 mumol/1 by a radioimmunometric method. Forty-nine (34%) patients had serum beta 2-M level > or = 3.0 mg/l. Of the patients with distal metastases 46% had elevated levels, compared with 19% with stage I disease. Serum beta 2-M correlated with histopathologic grade; 58% of the patients with poorly differentiated (grade 4) tumours had elevated levels compared with 18% in grade 1-2 tumours. Also tumour cell type was associated with serum beta 2-M; 52% of the patients with plasmic tumours had elevated levels compared with 6% in the clear cell type. In a univariate prognostic analysis elevated serum beta 2-M level was inversely correlated with survival time. Using a multivariate analysis the strong prognostic factors were clinical stage and tumour diameter. Weaker factors were age and cell type, whereas the prognostic value of serum beta 2-M disappeared. However, if tumour cell type was excluded from the analysis, serum beta 2-M was identified as a prognostic factor.